JP2021146291A - Extrusion method - Google Patents

Abstract

To provide an extrusion method capable of adjusting a thickness of a discharge material relatively easily and accurately.SOLUTION: An extrusion method using a die formed with a slot for discharging a fluid material, comprises: an adjusting step of adjusting height of the slot in order to adjust thickness of a discharge material discharged from the slot, in which a thickness d1n at a position n of arbitrary positions 1 to N in a direction orthogonal to a flow direction of the discharge material is calculated using a predetermined formulas (1) and (2); and a step of determining the height of the slot so that a difference e={e1 ... eN} between a calculated thickness d1={d11 ... d1N} calculated using a predetermined formula (3), and a target value of thickness dref={dref1 ... drefN} becomes small.SELECTED DRAWING: None

Description

The present invention relates to an extrusion method.

Conventionally, dies having slots for discharging fluids have been used in the manufacture of various products. For example, a coating device called a die coater provided with the die is used to form a coating film on the surface of a film or the like. Further, a die called a T die for extruding the molten resin into a film is used for producing a film.

The manufacturing method using such a die includes a step of adjusting the thickness of the discharged material discharged from the slot to a desired value. For example, Patent Document 1 describes a manufacturing method including an adjusting step of adjusting the height of the slot in order to adjust the thickness of the discharged material discharged from the slot.

Japanese Unexamined Patent Publication No. 2006-346649

However, conventionally, the adjustment of the thickness of the discharged material depends on the intuition of the operator, and there is a problem that it is difficult to adjust the discharged material to a desired thickness. Specifically, when the height of the slot at a position corresponding to the thickness is adjusted in order to change the thickness of a part of the discharged material to a desired value, the thickness of the slot at another position also changes. There is a problem that it will end up. That is, even if the thickness of a part of the discharged material is adjusted to a desired thickness, there is a problem that the thickness of another part that does not need to be changed is changed.
Further, in the extrusion method using the die, not only the thickness of the discharged product may be made uniform, but also the thickness of the discharged product may be partially changed. There is a problem with the adjustment of.

In view of the above problems, it is an object of the present invention to provide an extrusion method capable of adjusting the thickness of the discharged material relatively easily and accurately.

As a result of diligent studies by the present inventors, it was found that the amount of change in the height of the slot and the amount of change in the thickness of the discharged material before and after adjusting the height of the slot are in a proportional relationship, and complete the present invention. It came to.

ｄ_１ｎ：調節後の前記吐出物の計算厚みｄ_１＝｛ｄ_１１・・・ｄ_１Ｎ｝の位置ｎにおける値
ｄ_１ａｖｅ：ｄ_１＝｛ｄ_１１・・・ｄ_１Ｎ｝の平均値
Ｋ：比例定数
ｈ_１ｎ：仮想の調節後の前記スロットの高さｈ_１＝｛ｈ_１１・・・ｈ_１Ｎ｝の位置ｎにおける値
ｈ_１ａｖｅ：ｈ_１＝｛ｈ_１１・・・ｈ_１Ｎ｝の平均値
ｈ_０ｎ：調節前の前記スロットの高さｈ_０＝｛ｈ_０１・・・ｈ_０Ｎ｝の位置ｎにおける値
ｈ_０ａｖｅ：ｈ_０＝｛ｈ_０１・・・ｈ_０Ｎ｝の平均値
ｄ_０ｎ：調節前の前記吐出物の厚みｄ_０＝｛ｄ_０１・・・ｄ_０Ｎ｝の位置ｎにおける値
ｄ_０ａｖｅ：ｄ_０＝｛ｄ_０１・・・ｄ_０Ｎ｝の平均値
ｖ：前記流体物の粘性指数

ｅ_ｎ：前記差ｅ＝｛ｅ_１・・・ｅ_Ｎ｝の位置ｎにおける値
ｄ_ｒｅｆｎ：前記吐出物の厚みの目標値ｄ_ｒｅｆ＝｛ｄ_ｒｅｆ１・・・ｄ_ｒｅｆＮ｝の位置ｎにおける値 The extrusion method according to the present invention is
An extrusion method that uses a die with slots for discharging fluid.
In order to adjust the thickness of the discharged material discharged from the slot, an adjustment step of adjusting the height of the slot is provided.
_{In the adjusting step, the thickness d 1n at} the position n of the arbitrary positions 1 to N in the direction orthogonal to the flow direction of the discharged material is calculated by the following equations (1) and (2), and the following equation (3) in calculated calculated thickness _d 1 ₌ is _{d 11 ··· d _1N} and the difference between the target value of the thickness _{d ref = {d ref1 ··· d} refN} e = {e 1 ··· e N} A step of determining the height of the slot so as to be small is included.

d _1n : Calculated thickness of the discharged product after adjustment d ₁ = {d ₁₁ ... d _1N } value at position n d _1ave : d ₁ = {d ₁₁ ... d _1N } average value K: proportional Constant h _1n : Value at position n of the slot height h ₁ = {h ₁₁ ... h _{1N } after virtual adjustment h 1ave} : h ₁ = {h ₁₁ ... h _1N } average value h _0n : Value at position n of the slot height h ₀ = {h ₀₁ ... h _{0N } before adjustment h 0ave} : h ₀ = {h ₀₁ ... h _0N } average value d _0n : Before adjustment The average value of the value d _0ave : d ₀ = {d ₀₁ ... d _0N } at the position n of the thickness d ₀ = {d ₀₁ ... d _0N } of the discharged product v: Viscosity index of the fluid

e _n: the difference _{e = {e 1 ··· e N} } value _d at the position n of _refn: value at a position n of the discharge of the target value of the thickness _{d ref = {d ref1 ··· d} refN}

According to such a configuration, the height h _{0 of the slot before adjustment, the thickness d 0} of the discharged material before adjustment, and the value of the proportionality constant K calculated by the equation (2) are examined, and the value is calculated by the equation (1). Since the height of the slot is determined based on the difference e between the calculated thickness d ₁ and the target value d _ref of the thickness, the thickness of the discharged product can be adjusted relatively easily and accurately.

The extrusion method according to the present invention is preferably
_{H 1} = {h ₁₁ ... h _1N }, which minimizes the sum of the squares of the difference e = {e ₁ ... e _N } represented by the following equation (4), was obtained, and the above was obtained based on the _{h 1.} Determine the height of the slot.

_{According to such a configuration, the height of the slot is determined based on h 1 at} which the sum of the squares of the differences e represented by the equation (4) is minimized, so that the thickness of the discharged product can be adjusted more accurately. Can be done.

As described above, according to the present invention, it is possible to provide an extrusion method in which the thickness of the discharged product can be adjusted relatively easily and accurately.

FIG. 1 is a schematic perspective view of a die used in the extrusion method according to the embodiment. FIG. 2 is an exploded perspective view of the die of FIG. FIG. 3 is a schematic cross-sectional view of the die of FIG. 1 taken along line III-III. FIG. 4 is a graph for comparing changes in slot height and coating film thickness before and after adjustment in Example 1. FIG. 5 is a graph for comparing changes in the thickness of the coating film before and after the adjustment of Comparative Example 1. FIG. 6 is a graph for comparing changes in slot height and coating film thickness before and after adjustment in Example 2.

Hereinafter, the extrusion method according to the embodiment of the present invention will be described with reference to the drawings.

In the extrusion method according to the present embodiment, a coating liquid as a fluid is applied to the surface of an object to be coated such as film F by using a coating device called a die coater 1 as shown in FIGS. 1 to 3. This is a method of forming a coating film as a discharge material to be formed on the surface of the film F.

The die coater 1 includes a die 10 in which a slot 11 for discharging the coating liquid is formed. The die 10 coats a film F supported by a roller member or the like with a coating liquid discharged from the slot 11 on an object to be coated such as the film F running so as to be close to the opening 110 of the slot 11. Therefore, it is configured to form a coating film on the surface of the film F. The die 10 is formed so that the discharge portion 13 in which the opening 110 of the slot 11 is formed projects toward the object to be coated such as the film F. In the present embodiment, the die 10 has a first die block 20 (lower die block in the figure) and a second die block 30 (upper die block in the figure), and each die block. A slot 11 is formed between the two. Hereinafter, the direction in which the film F or the coating film flows may be referred to as MD, and the direction orthogonal to MD may be referred to as TD. Further, the height of the opening 110 of the slot 11 is defined as the height h of the slot 11.

The die 10 of the present embodiment further has an adjusting mechanism 50 for adjusting the height h of the slot 11 on the side of the second die block 30. In the present embodiment, the adjusting mechanism 50 is a plurality of slits 51 arranged in the second die block 30 along the width direction of the slot 11 and a plurality of adjusting the height h of the slot 11 by adjusting the distance between the slits 51. It has an adjusting screw 52 of. The plurality of adjusting screws 52 are arranged along the extending direction of the slit 51 (in other words, along the width direction of the slot 11), and the adjusting screws 52 rotate to advance or retract the slit 51. The interval is expanded or contracted, and the height h of the slot 11 is expanded or contracted accordingly.

As the adjusting screw 52, for example, a differential screw 52 is preferably used, which facilitates fine adjustment of the height h of the slot 11. The differential screw 52 has an external screw 521 formed in a hollow shape and an internal screw 522 formed so as to be screwed inside the external screw 521, and the external screw 521 and the internal screw 522 have their respective pitches. Are formed so that the sizes of the screws are different. As a result, when the external screw 521 is rotated once, the slit 51 expands and contracts by the pitch difference between the external screw 521 and the internal screw 522.

As shown in FIG. 2, in the present embodiment, the die 10 has a plate-shaped shim member 40 arranged so as to be sandwiched between the first die block 20 and the second die block 30. doing. The shim member 40 is formed in a C shape so as to open toward the opening 110 of the slot 11. The width of the coating film of the die 10 can be adjusted by adjusting the width of the opening 42 of the shim member 40.

The height h of the slot 11 is usually adjustable to 0.01 to 5 mm. The width of the slot 11 is usually set to 200 to 5000 mm.
The number of adjusting screws 52 is usually 3 to 90. The distance between the centers of rotation axes of the adjusting screws 52 is usually set to 10 to 400 mm. The distances between the centers of rotation axes are preferably equal, but may be different. In this embodiment, the adjusting mechanism 50 has N adjusting screws 52. In the following, the positions of the slots 11 and the positions of the coating film corresponding to the 1 to N adjusting screws 52 are referred to as positions 1 to N.

As shown in FIG. 3, the first die block 20 is formed in a concave shape for temporarily storing the coating liquid supplied from the accommodating portion (not shown) for accommodating the coating liquid via the passage 21. It has a cavity 22 that has been formed. The cavity 22 is connected to the slot 11.

Of the first die block 20 and the second die block 30, at least the second die block 30 may be manufactured of a material that can be elastically deformed by a pressing force such as an adjusting screw 52, and is usually made of stainless steel or the like. Manufactured from metal. Further, the shim member 40 is usually manufactured of a metal leaf such as stainless steel or brass or a plastic film such as polyethylene terephthalate.

Examples of the coating liquid include a polymer solution. The viscosity of the coating liquid is usually set to 0.0005 to 200 Pa · s, preferably 0.001 to 100 Pa · s. The viscosity shall be measured with a rheometer (manufactured by HAAKE). The measurement conditions are a shear rate of 1 [1 / s] and a temperature of 20 ° C.

Next, the extrusion method according to this embodiment will be described in detail.

The extrusion method of this embodiment is a coating method using a die coater 1 for forming a coating film on the surface of an object to be coated such as film F. In the coating method, the height h of the slot 11 is adjusted in order to adjust the thickness d of the coating film formed on the surface of the film F by ejecting the coating liquid from the slot 11. An adjustment step P and an extrusion step of extruding the coating liquid after the adjustment step P are provided. In this embodiment, the flow rate of the coating liquid supplied from the accommodating portion of the die coater 1 is constant.

In the present embodiment, the flow rate of the coating liquid preferably means a mass flow rate. Further, the constant flow rate of the coating liquid includes the case where the value calculated by [maximum flow rate-minimum flow rate] / average flow rate is 0.2 or less, preferably 0.1 or less during steady operation. It shall be muted.

In the adjustment step P, the height h ₀ = {h ₀₁ ... h _{0N } of the slot 11 at the positions 1 to N before the adjustment and the thickness d 0} = {d ₀₁ of the coating film at the positions 1 to N before the adjustment. ... d _0N } and the proportional constant K that associates the amount of change in the height h of the slot 11 and the amount of change in the thickness d of the coating film with the data acquisition step P1 are calculated by the following equation (2). _{The thickness d 1n} of the coating film at the position n of the steps P2 and positions 1 to N is calculated by the following formula (1), and the calculated thickness d ₁ = {d ₁₁ ... · _d as _1N} and the difference between the coating film of the target value of the thickness _{d ref = {d ref1 ··· d} refN} e = {e 1 ··· e N} becomes smaller, the height of the slot 11 It has a height determination step P3 for determining h.

d _1n represents the value at the position n of _{the calculated thickness d 1} = {d ₁₁ ... d _1N } of the coated film after adjustment.
d _1ave represents the average value of d ₁ = {d ₁₁ ... d _1N}. In the present embodiment, since the flow rate of the coating liquid is constant, it may be regarded as _{d 1ave} = d _0ave.
K represents a constant of proportionality.
h _1n represents the value at the position n of _{the height h 1} = {h ₁₁ ... h _1N } of the slot 11 after the virtual adjustment.
h _1ave represents the average value of h ₁ = {h ₁₁ ... h _1N}.
h _0n represents the value at the position n of the height h ₀ = {h ₀₁ ... h _{0N} of the slot before adjustment.}
h _0ave represents the average value of h ₀ = {h ₀₁ ... h _0N}.
d _0n represents the value at the position n of _{the thickness d 0} = {d ₀₁ ... d _0N } of the discharged product before adjustment.
d _0ave represents the average value of d ₀ = {d ₀₁ ... d _0N}.
v represents the viscosity index of the coating liquid.
e _n represents the value at a position n of the difference _{e = {e 1 ··· e N} }.
d _refn represents the value at a position n of the discharge of the target value of the thickness _{d ref = {d ref1 ··· d} refN}.

The above equation (1) is derived from the following equation (5). In the following equation (5), the left side represents the amount of change in the thickness d of the coating film, and the inside of the parentheses on the right side represents the amount of change in the height h of the slot 11, and each change amount is the proportionality constant K. Associated with.

The above formula (5) is based on the following formula (6) which holds when the coating liquid is assumed to be a Newtonian fluid.

Q represents the flow rate of the Newtonian fluid flowing through the slot 11.
W represents the coating width.
ΔP represents the differential pressure (p1-p2) between the pressure p1 of the Newtonian fluid at the upstream end 111 of the slot 11 and the pressure p2 of the Newtonian fluid at the opening 110.
μ represents the viscosity.
L represents the length of the slot, that is, the distance from the upstream end 111 to the opening 110.

As described above, the equation (6) shows that the rate of change dQ / Q of the flow rate of the Newtonian fluid is proportional to the rate of change dh / h of the height h of the slot 11. The above formula (1) is derived by regarding the rate of change dQ / Q of the flow rate in the formula (6) as the rate of change of the film thickness d of the coating liquid.

The above equation (2) is derived from the following equation (7) in which the above equation (6) is rewritten as a non-Newtonian fluid.

In the above formula (2), v represents the viscosity index of the coating liquid. Generally, the viscosity of a liquid such as a coating liquid is represented by the following approximate formula (8). In the present embodiment, the viscosity index v obtained by the approximate formula based on the viscosity data of the coating liquid measured by the rheometer is substituted into the formula (2) and used.

μ represents the viscosity [Pa · s] of the coating liquid.
η represents the zero shear viscosity [Pa · s] of the coating liquid.
γ represents the shear rate [1 / s].
v represents the viscosity index of the coating liquid.

[Data acquisition process P1]
In the data acquisition step P1, the thickness d of the coating film at the height h of the slot 11 before adjustment is measured. That is, the height of the slot 11 at positions 1 to N before adjustment h ₀ = {h ₀₁ ... h _0N } and the thickness of the coating film at positions 1 to N before adjustment d ₀ = {d ₀₁ ... d _0N } is measured.

As the measured value of the height h of the slot 11 at the positions 1 to N, the measured value of the height of the portion corresponding to the adjusting screw 52 is adopted. That is, in the TD, the height h of the slot 11 at the same position as the adjusting screw 52 is adopted as the measured value.

As the measured value of the coating film thickness d at positions 1 to N, the coating film thickness d at the same position as the adjusting screw 52 is adopted in TD. The thickness d of the coating film is measured by, for example, a linear gauge (manufactured by Ozaki Seisakusho).

In the data acquisition step P1, _further, calculates an average value _{d 0Ave} of _{h 0 = {h 01 ··· h} 0N} mean _{h 0Ave} and _d of _{0 = {d 01 ··· d 0N} }.

[Constant calculation step P2]
In the constant calculation step P2, the proportional constant K that associates the amount of change in the height h of the slot 11 with the amount of change in the thickness d of the coating film is calculated by the above equation (2). This proportionality constant K is a constant used by substituting into the equation (1) in the next height determination step P3.

[Height determination step P3]
In the height determination step P3, the thickness d _{1n at the} position n of the positions 1 to N is calculated by the above formula (1), and the calculated thickness d ₁ = {d ₁₁ ... d calculated by the above formula (3). as _1N} the difference _{e = {e} 1 ··· _{e N} a ₌ target thickness _{d ref {d ref1 ··· d refN} }} is reduced, the adjusted virtual at location 1~N slot Height h ₁ = {h ₁₁ ... h _1N } is calculated.

In the present embodiment, h ₁ = {h ₁₁ ... h _1N } is such that the sum of the squares of the difference e = {e ₁ ... e _{N} represented by the following equation (4) is minimized.} It is calculated by the least squares method. For example, h ₁ = {h ₁₁ ... h _1N } is calculated by giving an arbitrary initial value and using an Excel (registered trademark) solver. Then, based on the value of _{h 1} = {h ₁₁ ... h _{1N }, the height h 2} = {h ₂₁ ... h _2N } of the slot 11 after adjustment is determined. _{As the height h 2} = {h ₂₁ ... h _2N } of the slot 11 after adjustment, _{the value of h 1} = {h ₁₁ ... h _1N } may be adopted as it is, and h ₁ = {h. A value finely adjusted based on the value of ₁₁ ... h _{1N} may be adopted.}

As described above, according to the extrusion method of the present embodiment, the height of the slot 11 before adjustment h ₀ = {h ₀₁ ... h _0N }, and the thickness of the coating liquid before adjustment d ₀ = {d _01.・ ・ If the _{values of} d 0N} and the proportionality constant K calculated by the equation (2) are examined, the calculated thickness d ₁ = {d ₁₁ ... d _1N } calculated by the equation (1), and the thickness target. the value _{d ref = {d ref1 ··· d} refN} the difference _{e = {e 1 ··· e N} } height of the slot 11 on the basis of _{h 1 = {h 11 ··· h} 1N} of is determined , Since _{the height h 2} = {h ₂₁ ... h _2N } of the slot 11 after adjustment is determined based on the value of _{this h 1} = {h ₁₁ ... h _1N }, it is relatively easy. Moreover, the thickness of the coating liquid can be adjusted with high accuracy. Further, in the extrusion method of the present embodiment, in addition to adjusting the thickness d of the coating liquid to a target uniform thickness, the thickness d of the coating liquid can also be adjusted to a target non-uniform thickness. Are better.

The extrusion method according to the present invention is not limited to the above embodiment. Further, the extrusion method according to the present invention is not limited by the above-mentioned effects. The extrusion method according to the present invention can be variously modified without departing from the gist of the present invention.

For example, in the above embodiment, the coating method using the die coater 1 has been described, but a resin film molding method using a T-die or the like for extruding the molten resin may be used. In this case, the viscosity of the molten resin is preferably 1000 to 5000 Pa · s.

Further, in the above embodiment, the mode in which the height h of the slot 11 is adjusted by the adjusting mechanism 50 having the slit 51 and the adjusting screw 52 is shown, but the present invention is not limited to this. As another adjusting mechanism 50, a heat bolt may be adopted instead of the adjusting screw 52. In addition, for example, the shim member 40 and each die block may be processed to adjust the height h of the slot. Further, the data acquisition step P1 and the constant calculation step P2 are carried out using the prototype die coater 1, and the die coater 1 having h set in order to obtain the desired coating film thickness d in the height determination step P3 is obtained. It may be manufactured.

Further, in the above embodiment, the least squares method is shown as an approximation method, but in addition to this, for example, Newton's method may be adopted.

Hereinafter, the present invention will be further described by showing examples.

In this example, a method of forming a coating film using a die coater was examined.

[Coating equipment]
The die coater used in this embodiment is made of stainless steel, and a slot having a width of 1300 mm is formed between the first die block and the second die block. It has a slit provided in the die block and 26 adjusting screws (that is, positions 1 to 26 at N = 26) (distance between the centers of rotation axes: constant at 50 mm) arranged over the TD.

[Coating conditions]
Under the coating conditions shown in Table 1, an acrylic polymer dissolved in a solvent was applied as a coating liquid on the surface of the film as an object to be coated to form a coating film made of an acrylic polymer as a discharge product.

[Example 1]
In the first embodiment, a method of adjusting the height of the slot so that the thickness of the coating film changes from a non-uniform state to a uniform state is illustrated.

(Data acquisition process P1)
Slot height at positions 1-26 before adjustment h ₀ = {h ₀₁ ... h _{0_26} } and thickness of coating film at positions 1-26 before adjustment d ₀ = {d ₀₁ ... d _{0_26} } Was measured. The measurement results are shown in Table 2.

(Constant calculation step P2)
The viscosity index v of the coating liquid used in this example was calculated by the above formula (8), and this viscosity index v was substituted into the above formula (2) to calculate the proportionality constant K. As shown in Table 2, K = 4.89.

(Height determination step P3)
Sets a target value of the thickness of the coating films shown in Table _{2 d ref = {d ref1 ···} d ref26}, the equation (1), by the least squares method using (3) and (4), calculating positions 1-26 thicknesses _{d 1 = {d 11 ··· d} 1_26} and the difference between the target value of the thickness _{d ref = {d ref1 ··· d} ref26} e = {e 1 ··· e 26} _{The adjusted slot height h 1} = {h ₁₁ ... h _{1_26} } at positions 1-26 was calculated so that the sum of the squares of was minimized. The calculation results are shown in Table 2 below.

(Extrusion process)
As the slot height h ₂ = {h ₂₁ ... h _2N }, h ₁ = {h ₁₁ ... h _{1_26} } calculated above was adopted to form a coating film on the film. The results of measuring the thickness after adjustment are shown in Table 2 and FIG.

As shown in Table 2 and FIG. 4, the thickness of the coating film before adjustment was in a non-uniform state near the width of 255 mm and the width of about 1125 mm, but the thickness of the coating film after adjustment was in the width direction. It was adjusted to a generally uniform condition over the period.

[Comparative Example 1]
In Comparative Example 1, the result of adjusting the slot height by a skilled worker without using this method is illustrated. In Comparative Example 1, _{the values of h 0} , d _0, and d _ref were set to the same values as in Example 1. Further, _{based on the measured values of h 0} and d ₀ , the height of the slot was adjusted with the adjusting screw five times. The results are shown in Table 3 and FIG.

As shown in Table 3 and FIG. 5, the result deviated from the target value in the width direction. In the width direction, the thickness that was smaller than the target became larger than the target, and the thickness that was larger than the target became smaller than the target, and it was found that it was difficult for the operator to make empirical adjustments.

Table 4 below summarizes the accuracy of the coating film thickness before and after the adjustment of Example 1 and Comparative Example 1. The thickness accuracy was calculated by [maximum thickness-minimum thickness] / average thickness × 100. From the results in Table 4, it was confirmed that the extrusion method of Example 1 was able to easily and accurately adjust the thickness of the coating film as compared with Comparative Example 1.

[Example 2]
In the second embodiment, a method of adjusting the height of the slot so that the thickness of the coating film changes from a uniform state to a non-uniform state is illustrated. The coating conditions were the conditions shown in Table 5. The results are shown in Table 6 and FIG.

As shown in Table 6 and FIG. 6, the thickness of the coating film after adjustment was adjusted to a substantially non-uniform state of the target over the width direction.

1: Die coater,
10: Die, 11: Slot, 110: Opening, 111: Upstream end, 13: Discharge part,
20: 1st die block, 21: passage, 22: cavity,
30: Second die block,
40: shim member, 42: opening,
50: Adjustment mechanism, 51: Slit, 52: Adjustment screw, 521: External screw, 522: Internal screw

Claims (2)

An extrusion method that uses a die with slots for discharging fluid.
In order to adjust the thickness of the discharged material discharged from the slot, an adjustment step of adjusting the height of the slot is provided.
_{In the adjusting step, the thickness d 1n at} the position n of the arbitrary positions 1 to N in the direction orthogonal to the flow direction of the discharged material is calculated by the following equations (1) and (2), and the following equation (3) in calculated calculated thickness _d 1 ₌ is _{d 11 ··· d _1N} and the difference between the target value of the thickness _{d ref = {d ref1 ··· d} refN} e = {e 1 ··· e N} An extrusion method comprising the step of determining the height of the slot so as to be smaller.

d _1n : Calculated thickness of the discharged product after adjustment d ₁ = {d ₁₁ ... d _1N } value at position n d _1ave : d ₁ = {d ₁₁ ... d _1N } average value K: proportional Constant h _1n : Value at position n of the slot height h ₁ = {h ₁₁ ... h _{1N } after virtual adjustment h 1ave} : h ₁ = {h ₁₁ ... h _1N } average value h _0n : Value at position n of the slot height h ₀ = {h ₀₁ ... h _{0N } before adjustment h 0ave} : h ₀ = {h ₀₁ ... h _0N } average value d _0n : Before adjustment The average value of the value d _0ave : d ₀ = {d ₀₁ ... d _0N } at the position n of the thickness d ₀ = {d ₀₁ ... d _0N } of the discharged product v: Viscosity index of the fluid

e _n: the difference _{e = {e 1 ··· e N} } value _d at the position n of _refn: value at a position n of the discharge of the target value of the thickness _{d ref = {d ref1 ··· d} refN} _{H 1} = {h ₁₁ ... h _1N }, which minimizes the sum of the squares of the difference e = {e ₁ ... e _N } represented by the following equation (4), was obtained, and the above was obtained based on the _{h 1.} The extrusion method according to claim 1, wherein the height of the slot is determined.

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